1. Field of the Invention
This invention relates to a floor mat, particularly used for dusting of shoe bottoms by being laid in an entrance or an inlet of housings and shops.
2. Description of the Prior Art
Many floor mats consist of a base cloth, piles tufted thereto and a backing of synthetic rubber fixing and tufted system. They are used as laid on an entrance and exit to prevent intrusion of dusts to indoors from outside in shops, housings and offices.
Backings of synthetic rubbers are generally integrated by laying tufted piles and an unvulcanized rubber sheet and heating them under pressure.
When a mat is made by such a method, the sizes of the original portion of the mat and a rubber portion are fixed at the time of heating under pressure, and after cooling, at ordinary temperature of use, the product gives rise to distortion from differences in the coefficient of linear expansion between the rubber and the fiber, or it remains as an internal stress. Consequently, the distortion appears as a dimensional change such as waving and curling.
In addition to the dimensional difference at the time of manufacturing a mat, a strain from the shrinkage (the rubber is difficult to shrink as compared with the fiber) of the fibers owing to repeated use (due to the repetition of washing and drying) is added. A complex strain occurs on the whole mat, causing waving and curling. Since these shorten the life of the rental mat, this poses a great problem.